Two-temperature refrigerating apparatus



July 12, 1938. L. B. M. BUCHANAN I"WOTEMPEHFKATURE: REFRIGERATING APPARATUS Filed NOV. 11, 1956 PM. a.

INVENTOR LESLIE BM. BUCHRNHN.

ATTOR EY Patented July 12, 1938 PATENT OFFICE TWO-TEMPERATURE REFRIGERATING APPARATUS Leslie B. M. Buchanan signor to Westinghou Springfield, Mass, asse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 11, 1936, Serial No. 110,203

6 Claims.

My invention relates to two temperature refrigerating apparatus employing a multiple inlet compressor mechanism and it has for an object to provide improved apparatus of this character.

A further object of my invention is to provide an improved refrigerating system employing a plurality of evaporators and a ported cylinder compressor for withdrawing refrigerant vaporized at diflerent pressures in the evaporators.

A still further object of the invention is to provide improved means for controlling the flow of refrigerant vaporized at different pressures in the evaporators,'to the inlet ports of a ported cylinder compressor.

These and other objects are effected by my invention as will be apparent. from the following description and claims. taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a diagrammatic view of a two temperature refrigerating system arranged in accordance with my invention; and,

Fig. 2 is a sectional view of a ported cylinder complressor employed in the ,system shown in Fig.

Referring now to Fig. 1, the numerals Ill and II indicate zones or chambers of a refrigerator that are refrigerated by relatively low and high temperature evaporators l2 and i3. The latter are supplied with condensed refrigerant from a condenser l4, cooled in any suitable manner such as, for example, by a fan IS. The condenser delines an element of a refrigerant condensing unit, indicated generally at I6 and including a compressor ll driven by a motor l8.

A portion of the compressor I1 is shown in section in Fig. 2 and preferably includes a cylinder I9 that is ported as shown at 2|. A piston 22 is disposed in the cylinder l9 and may be reciprocated therein in any well known manner such as, for example, by a connecting rod 23. The cylinder I9 is provided with a valve structure, generally indicated at 24, and a head 25, the latter being provided with inlet and outlet chambers .26 and 21, respectively. The chambers 28 and 21 communicate, respectively, with the evaporator I2 and the condenser l4 by means of conduits 28 and 29. The port 2| in the cylinder IScommunicates with the high temperature evaporator 56'" I3 by means of a conduit 3i.

The valve structure 24 includes a valve plate 32 and inlet and outlet valves 33 and 34, respec- ,tively. The valves 33 and 34 control the flow of i-refrigerantthrough passages 35 and 35 formed in the plate 32 between the chambers 23 and 2] and the cylinder I9. The operation and construction of a valve structure of the type shown at 24 is well known in the art and it is, therefore, not necessary to further describe its construction and operation. It will be understood that the specific form of compressor 'valve structure forms no part of my invention and that other valve arrangements may be employed.

The apparatus described in the foregoing operates on the well known compressor-condenserexpander refrigerating cycle wherein refrigerant vaporized at relatively low pressure in the low temperature evaporator i2 is drawn into the cylinder I 9 through the conduit 28 and valve 33 as the piston moves downwardly. As the piston 22 passes beneath the port 2|, refrigerant vaporized at relatively high pressure in the evaporator l3 enters the cylinder l9 through the conduit 3! and port 2| and compresses the low pressure gas in the cylinder l9 to a value substantially equal to the value of the higher pressure gas. Accordingly, when vaporized refrigerant is withdrawn from both evaporators l2 and I3, the density of the gas in the cylinder I9 at the beginning of the compression stroke is substantially equal to the density of the higher pressure gas withdrawn from the high temperature evaporator l3.

The gas compressed in the cylinder l9 by the piston 22 is discharged through the valve 34 and the conduit 29 into the condenser i4, wherein it is cooled by the fan l and is condensed at relatively high pressure. A reservoir 31 may be provided for the condensed refrigerant and a conduit 38 communicating therewith conducts the condensed refrigerant to the evaporators l2 and i3. Suitable expansion devices, such as, for example, conventional low side float valves 4] and 42, are provided for controlling the flow of refrigerant from the conduit 38 to. the respective evaporators i2 and, I3. The float valves 4| and 42 function to admit refrigerant to their associated evaporators l2 and I3 in response to the level of the liquid therein.

The pressure of the condensed refrigerant is reduced as it passes through the valves 4| and 42 to the values maintained in the evaporators by the compressor ll. vaporization of the refrigerant at relatively low pressures in the respective evaporators l2 and I3 is effected, whereby heat is abstracted from the chambers l0 and II.

The control 01' the operation ofthe compressor I1 and of vaporization in the evaporators i2 and I3 will now be described. The temperatures within the low and higher temperature zones or predetermined temperature limits.

chambers l and II may be maintained between predetermined limits by means of thermostats 43 and 44 shown by way of example of the exp-ansible gas type. These thermostats 43 and 44 are shown in their simplest form for the sake of clearness and certain refinements such as, for example, quick make and break mechanisms for the switch contacts have been omitted. The thermostat 43 includes an expansible bellows 45 connected to a bulb 48 which is disposed in the chamber l0, preferably in contact with the evaporator |2. A volatile fluid is contained in the bulb 46, the pressure of which increases and decreases as the temperature of the bulb 46 increases and decreases. Accordingly, the bellows 45' expands and contracts with increases and decreases in the temperature within the chamber I8.

The thermostat 43 includes switches 41 and 48, the former closing and the latter opening in response to a predetermined high temperature within the chamber l0. Conversely, the switch 41 is opened and the switch 48 is closed in response to a predetermined low temperature within the chamber Ill. The thermostat 43, therefore, operates to maintain the chamber |0 within The temperatures at which the switches 41 and 48 are operated may be varied by means of an adjustable spring shown at 49. It is to be understood that other forms of thermostats per so may be employed in my improved refrigerating system and that the gas type thermostats which I have disclosed" are shown by way of example.

The thermostat 44 is similar to the thermostat 43 and includes a bellows connected to a bulb 52 disposed in the chamber A switch 53 is actuated by the bellows 5| in such manner that it opens and closes in response to predetermined low and high temperatures within the chamber respectively. An adjustment 54 similar to the adjustment 48 may be provided for the thermostat 44. v

The source of power for the motor I8 is represented by the line conductor L1 and L2. One terminal of the motor |8 is connected to the line conductor L2 and its other terminal is connected to a conductor 55 that extends to the switches 53 and 41. The latter switches 53 and 41 are connected to the line conductor L1, as shown. Accordingly, when either thermostat 43 or 44 operates in response to the temperatures at which they close their respective switches 41 and 53, the motor I8 is energized by a circuit including line conductor L2, the motor l8, conductor 55, switches 41 or 53 and the line conductor Ll. Operation of the compressor I1 is effected until the switches 41 or 53 are opened in response to the minimum temperature at which the thermostats 43 or 44 are adjusted.

There may be periods when one evaporator requires cooling while the other evaporator is satlsfied and, therefore, means are provided for controlling the operation of one independently of the other. Accordingly, valves 56 and 51 actuated by solenoids 58 and 58, respectively, are disposed in the suction conduits 28 and 3|. The operation of electrically operated valves of this type are well known and no detailed description of them is necessary other than to say that the valves are open when their respective solenoids are energized and are closed when the solenoids are deenergized.

One terminal of each solenoid 58 and 59 is connected to the line conductor L: by means of a conductor 5|. The opposite terminal of the solenoid 58 is connected to the switch 41 which, when closed, effects energization of the solenoid 58 by completing its connection to the line conductor L1. The opposite terminal of the solenoid 59 is connected to a conductor 62 controlled by the switch 53 which, when closed connects the conductor 62 to the line conductor L1, whereby the solenoid 58 is energized.

When the thermostat switch 41 is closed, the compressor motor l8 and the solenoid 58 are energized. Accordingly, the compressor |1 operates to withdraw refrigerant from the evaporator |2 through the open valve 58. As the valve 51 is closed no refrigerant is withdrawn from the evaporator l3. During periods when the thermostat 44 eifects closure of the switch 53, and the switch 41 of thermostat 43 is open, the compressor is operated and withdraws refrigerant from the evaporator I3 through the valve 51. At this time, however, a relatively high vacuum may be produced in the compressor cylinder l9 prior to the time that the piston 22 opens the port 2| due to the fact that the valve 56 controlling flow ofvapor to the valve chamber 26 is closed.

In order that this condition may be obviated, I provide means shown by way of example, as a conduit 63, for connecting the suction conduits 28 and 3|. The connecting conduit 63 includes a valve 64 operated by a solenoid 65. During periods when the compressor operates in response to a demand for cooling by the thermostat 44 only, the valve 64 is open so' that the vapor from the higher temperature evaporator I3 is conveyed to the compressor |1 through the conduit 3| and a branch thereof defined by the conduits 63 and 28. Accordingly, vapor enters the cylinder 8 through the inlet valve 33 and the port 2|.

Energization of the solenoid 65 is controlled by the switch 41 of the thermostat 43 which switch is connected between the conductor 62 and one terminal of the solenoid 65. The other terminal' of the solenoid connects with the line conductor L2 as shown.

Operation The position of the various elements of the system as shown in the drawing indicates that the temperatures within the chambers l8 and l are below the values at which their respective thermostats operate to start the compressor. Accordingly, the compressor l1 and its motor |8 are inactive and the valves 55, 51 and B4 are closed as their solenoids 58, 58 and 65 are deenergized. Assume that the temperature of the evaporator l2 in the chambers ill rises to the value at which the thermostat '43 effects closing of the switch 41 and opening of'the switch 48. Closure of the switch 41 effects energization of the motor l8 and of the solenoid 58 so that refrigerant is withdrawn by the compressor H from the evaporator 2, the valve 56 being. open. At this time, no refrigerant is admitted to the cylinder I!) through the port 2| as the valve 51 is closed. Accordingly, the evaporator |3is inactive.

Assume the thermostat 44 closes the switch 53 in response to a demand for cooling in the chamber I, the solenoid 59 is energized and a. parallel circuit to the motor established through the switch 53. Accordingly, the valve 51 is opened and the compressor l1 operates to withdraw vaporized refrigerant from the evaporator l3 through the conduit 3| and the cylinder port 2|. As described heretofore, the higher pressure gas in the conduit 3| compresses the relatively low pressure gas in the cylinder l9 when the piston opens the port 2 l The gas conveyed through the conduit 29 to the condenser I4 is a mixture of the refrigerant vaporized in both evaporators.

Assume now that the temperature of the evaporator I2 is depressed to the value at which the thermostat opens the switch 41 and closes the switch 48. Operation of the compressor l1 continues as its motor I8 is energized through the closed switch 53 of the thermostat 44 but the solenoid 58 is deenergized and the valve 56, therefore, closes. Closure of the switch 48 energizes solenoid 65 so that its valve opens. Accordingly, vapor in the conduit 3| is admitted through the conduit 63 and valve 64 to the conduit 28. The higher temperature vapor, therefore, enters the cylinder I9 through the passage 35 in the valve structure 24 and through the port 2|.

As the temperature of the zone or chamber II is depressed to the desired value, the thermostat 44 operates to open the switch 53 whereby operation of the compressor I1 is terminated and the valves 64 and 51 are closed. The system is now inactive and remains so until operation is again effected by the thermostat 43 or 44.

From the foregoing, it will be apparent that refrigeration of the evaporators l2 and I! may be effected at any time either individually or together and that during periods when the higher temperature evaporator alone is operated, both of the inlet ports of the compressor I! are employed for the passage of refrigerant to the cylinder I9.

I have shown my improved refrigerating system including a compressor of the ported cylinder type but it will be understood that it is not so limited as other forms of compressors may be employed.

A ported cylinder compressor used in my improved system is efilciently operated during periods when both evaporators are active as the density of the gas compressed is at a relatively high value due to the mixture of the high and low pressure gas in the cylinder prior to the compression stroke. During periods when the high temperature evaporator is active-the load on the compressor motor is reduced as the higher temperature vapor is, at this time, admitted to the cylinder duringthe entire suction stroke of the piston and, therefore, the necessity of operating against a high vacuum in the compressor cylinder prior to the opening of the wall port thereof is obviated.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. In refrigerating apparatus, the combination of relatively high and low temperature refrigerant evaporators, a mechanism having first and second inlets for refrigerant vaporized in the evaporators, means for establishing communication between the low temperature evaporator and said first inlet during periods when the low temperature evaporator is active, means for also establishing communication between the higher temperature evaporator and said second inlet during periods when both of said evaporators are active and means for establishing communication a between the higher temperature evaporator and both of said inlets when only the higher temperature evaporator is active.

2. In apparatus for refrigerating low and high temperature zones of a refrigerator, the combination of relatively low and high temperature evaporators for cooling the low and high temperature zones, respectively, a compressor having first and second inlet ports for refrigerant vaporized in the evaporators, means responsive to demands for refrigeration within the zones and effective to establish communication between the low temperature evaporator and the first compressor port when the low temperature zone demands refrigeration, to establish communication between the low temperature evaporator and the first compressor port and between the high temperature evaporator and the second compressor port when both zones demand refrigeration and to establish communication between the high temperature evaporator and both of said compressor ports when the high temperature zone demands refrigeration and the low temperature zone is satisfied.

3. In refrigerating apparatus, the combination of a compressor having a cylinder and a piston therein, means for admitting vaporized refrigerant to the cylinder, said cylinder including a port opened and closed by said piston for also admitting vaporous refrigerant to the cylinder, a condenser for receiving refrigerant compressed in the cylinder, high and low temperature evaporators, means for conveying condensed refrigerant from the condenser to the evaporators, first and second conduits for conveying vaporous refrigerant from the low and high temperature evaporators to said refrigerant admitting means and said port, respectively, a conduit connecting said first and second conduits and a valve for controlling the flow of refrigerant in the connecting conduit.

4. In two temperature refrigerating apparatus, the combination of relatively high and low temperature evaporators, a compressor having a cylinder and a piston therein, means for reciprocating the piston'in the cylinder, said cylinder having a valved inlet adjacent an end thereof and an inlet port spaced from the valved inlet and opened and closed by the piston, means for conveying refrigerant vaporized in the low temperature evaporator to said valved inlet, means for conveying refrigerant vaporized in said high temperature evaporator to said inlet port, means for controlling the fiow of vaporous refrigerant in the respective refrigerant conveying means, means defining a passage connecting said valved inlet and said inlet port and means for controlling the flow of refrigerant vapor in the connecting passage.

5. In apparatus for refrigerating high and low temperature chambers of a refrigerator, the combination of relatively high and low temperature evaporators disposed for cooling the high and low temperature chambers, a compressor having a cylinder and a piston therein, means for reciprocating the piston in the cylinder, said cylinder having a valved inlet adjacent an end thereof and an inlet port spaced from the valved inlet and opened and closed by the piston, means for conveying refrigerant vaporized in the low temperature evaporator to said valved inlet, means for conveying refrigerant vaporized in said high temperature evaporator to said inlet port, means responsive to the temperature within the low temperature chamber for controlling the flow of vaporous refrigerant to said valved inlet,

pressor having a cylinder and a piston therein, said cylinder including an inlet for refrigerant vaporized in the low temperature evaporator and a port opened and closed by said piston for receiving refrigerant vaporized in said high temperature evaporator, first and second valves for controlling the flow of refrigerant from the low and high temperature evaporators to the inlet and port of the cylinder, respectively, and means responsive to the temperatures within said low and high temperature zones for controlling the operation of the respective first and second valves.

LESLIE B. M. BUCHANAN.

DISCLAIMER 2,123,497.Leslie B. M. Buchanan, Springfield, Mass.

Patent dated July 12, 1938.

ERA'IING APPARATUS.

TWO-TEMPERATURE REFRIG- Disclaimer filed January 13, 1939, by the assignee. Westinghouse Electric e6; lifanafacturing Company.

Hereby enters this disclaimer to claims 1 and 2 of the specification of said Letters [Ofiicial Gazette February 14, 1939.]

Patent.

pressor having a cylinder and a piston therein, said cylinder including an inlet for refrigerant vaporized in the low temperature evaporator and a port opened and closed by said piston for receiving refrigerant vaporized in said high temperature evaporator, first and second valves for controlling the flow of refrigerant from the low and high temperature evaporators to the inlet and port of the cylinder, respectively, and means responsive to the temperatures within said low and high temperature zones for controlling the operation of the respective first and second valves.

LESLIE B. M. BUCHANAN.

DISCLAIMER 2,123,497.Leslie B. M. Buchanan, Springfield, Mass.

Patent dated July 12, 1938.

ERA'IING APPARATUS.

TWO-TEMPERATURE REFRIG- Disclaimer filed January 13, 1939, by the assignee. Westinghouse Electric e6; lifanafacturing Company.

Hereby enters this disclaimer to claims 1 and 2 of the specification of said Letters [Ofiicial Gazette February 14, 1939.]

Patent. 

